People seem to get confused over what constitutes a concrete, honest to god promise, and what constitutes a design goal. Nothing was ever promised, set in stone, and absolutely told to us that we were going to have the tools to make 5E into whatever edition we wanted. We were told that they were looking into modular rulesets to help emulate the feel of multiple editions at the table. In some ways, that's been accomplished right in the PHB. And there may be other rules that help emulate older editions in the DMG. But design intentions and goals change over the course of development. Look no further than 4th edition and how incredibly different it was from the initial talk and design planning we heard about, as well as how different it was form it's "beta" products (Tome of Battle and Star Wars Saga Edition).
Nobody lied, and there's nothing saying these rules aren't available in some form. Design changes with development, and getting hung up on "promises" and comments made one or two years ago across the ongoing development of a game is silly.